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AnsweredHot!How not to kill a dsPIC33EP?

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mpgmike
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Re: How not to kill a dsPIC33EP? 2019/11/16 05:50:08 (permalink)
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You got me thinking.  I'm using a heat gun to pop the fried PICs off the board.  I thought maybe the 4-layer board might be delaminating and I could have lost a ground connection to one of the PIC pins.  I checked with an ohm meter and all 4 grounds are solid.

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crosland
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Re: How not to kill a dsPIC33EP? 2019/11/16 05:59:43 (permalink)
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When you supply power from the ICD/PICKit, you are disconnecting the USB power source, aren't you?
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mpgmike
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Re: How not to kill a dsPIC33EP? 2019/11/16 06:21:47 (permalink)
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I am not using USB power, no connection on the board.  Plus, I have never had a USB cable and ICSP connected at the same time.  This is a 1-off research project for proof of concept.  Basically I'm fuel injecting a single cylinder generator and controlling ignition timing with an automotive type ignition coil (plus a few other things).  The USB is for monitoring and tuning.  Thus no need for USB supplied power.

I don't need the world to know my name, but I want to live a life so all my great-grandchildren proudly remember me.
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sborden
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Re: How not to kill a dsPIC33EP? 2019/11/21 05:26:01 (permalink)
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You might consider posting schematics at this point. If you can, of course.
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mpgmike
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Re: How not to kill a dsPIC33EP? 2019/11/21 09:43:28 (permalink)
5 (1)
When dsPIC #7 wouldn't even program a first time, I pulled it back off & started checking traces.  I found damage.  I don't know if it happened between #1 & #2 or #6 & #7, but I need to order a new board (4-layer = $300 US!).  I know there were errors with software & hardware when the 1st dsPIC went on.  I started correcting things as I found them, replacing the dsPIC several times along the way.  I'm holding off 'till the new board is here & I have a chance to test it.
 
FWIW, I pored over the Microchip dsPIC33E USB Dev Board to see how it was configured.  That prompted a few changes in how I am configuring the new PCB.

I don't need the world to know my name, but I want to live a life so all my great-grandchildren proudly remember me.
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Antipodean
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Re: How not to kill a dsPIC33EP? 2019/11/21 10:25:55 (permalink)
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mpgmike
 but I need to order a new board (4-layer = $300 US!). 



Have a look at https://jlcpcb.com/
 
A colleague has used them with good results.
 

Do not use my alias in your message body when replying, your message will disappear ...

Alan
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NorthGuy
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Re: How not to kill a dsPIC33EP? 2019/11/21 10:44:04 (permalink)
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mpgmike
I found damage.  I don't know if it happened between #1 & #2 or #6 & #7, but I need to order a new board (4-layer = $300 US!).



May be it was there from the beginning and caused all these problems.
 
Since you're designing a new board, I would add a footprint for a capacitor between PGC and ground not too far from the PIC, just in case.
 
WellPCB has good prices for high quality 4+ layer boards.
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du00000001
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Re: How not to kill a dsPIC33EP? 2019/11/21 10:51:10 (permalink)
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@ mpgmike
If this board is your own design, I'd consider applying (2-layer) PIMs (just as on the Explorer 16/32). You could even copy the pinout of these PIMs. This would allow for easier exchanging microcontrollers - even forusing microcontrollers with differing pin counts. And the PIMs are ok with 2 layers.
 
BTW: 4 layers? Until now I always got away with 2 layers unless space was extremely critical. But for prototyping I prefer a somewhat larger board with options for probing etc.

PEBKAC / EBKAC / POBCAK / PICNIC (eventually see en.wikipedia.org)
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mpgmike
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Re: How not to kill a dsPIC33EP? 2019/11/21 17:16:41 (permalink)
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I already ordered a new board.  I'm using 4 layers for 2 reasons; there's too much going on, I need the power & ground planes because it'd be a real pain to route on a 2-layer board.  Secondly, there's a boost converter and several PWM circuits that create lots of noise.  The extra planes help with EMI suppression.  Thanks for the info, though.  Should be here mid-next week (I surely hope!).  Using the time to replace head gaskets in a friend's Caddy, with new steel threads in the aluminum block, head studs, and MLS gaskets.  I'll reinforce the mains while I have it apart.  Same problem, aluminum threads in the block.

I don't need the world to know my name, but I want to live a life so all my great-grandchildren proudly remember me.
#29
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